/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.tika.example;

import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.Key;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.xml.namespace.QName;

import org.apache.tika.detect.Detector;
import org.apache.tika.detect.XmlRootExtractor;
import org.apache.tika.io.LookaheadInputStream;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.mime.MediaType;

public class EncryptedPrescriptionDetector implements Detector {
    private static final long serialVersionUID = -1709652690773421147L;

    public MediaType detect(InputStream stream, Metadata metadata)
            throws IOException {
        Key key = Pharmacy.getKey();
        MediaType type = MediaType.OCTET_STREAM;

        try (InputStream lookahead = new LookaheadInputStream(stream, 1024)) {
            Cipher cipher = Cipher.getInstance("RSA");

            cipher.init(Cipher.DECRYPT_MODE, key);
            InputStream decrypted = new CipherInputStream(lookahead, cipher);

            QName name = new XmlRootExtractor().extractRootElement(decrypted);
            if (name != null
                    && "http://example.com/xpd".equals(name.getNamespaceURI())
                    && "prescription".equals(name.getLocalPart())) {
                type = MediaType.application("x-prescription");
            }
        } catch (GeneralSecurityException e) {
            // unable to decrypt, fall through
        }
        return type;
    }
}